Conservative commentator Patrick J. Buchanan is moving closer to a 1996 White House run and serving notice to other GOP prospects that he will employ the bare-knuckles style he used in his 1992 primary challenge to President Bush.

Aides said a Buchanan exploratory committee would be filed with the Federal Election Commission Thursday. And he will spend the weekend in New Hampshire, where his 37 percent in the 1992 GOP primary exposed Bush's weakness among conservatives.In a statement to accompany the filing, Buchanan promised to aggressively promote the Republican Party's opposition to abortion. And in a warning to other candidates who shy away from debating social issues, he said, "It is time the Republican Party stops backing away from its pro-life platform."

Buchanan, in the statement, also pledged to dedicate his campaign to "economic patriotism and a foreign and trade policy that looks out for the interests of Main Street Americans rather than Wall Street multinationals and foreign regimes."

So far, the GOP field includes Senate Majority Leader Bob Dole of Kansas, Sen. Phil Gramm of Texas and former Gov. Lamar Alexander of Tennessee. Sens. Arlen Specter of Pennsylvania and Richard Lugar of Indiana say they are likely to run. A few GOP governors are looking at the race, and conservative Rep. Bob Dornan of California says he, too, plans to run.

Buchanan worked as a communications aide in the Nixon, Ford and Reagan White Houses. His filing of an exploratory committee will force him to give up his media jobs, as a host on CNN's "Crossfire" program and a syndicated newspaper column.